Excavating machine



March 9, 193 7.

D. J. SHELTON 2,073,539

EXCAVATING MACHINE Filed April 16, "1956 Patented Mar. 9, 1937 UNITED STATES EXCAVATING MACHINE Dwight J. Shelton, Marion, Ohio, assignor to The Marion Steam Shovel Company, Marion, Ohio,

a corporation of Ohio Application April 16, 1936, Serial No. 74,692

10 Claims.

This invention relates to an excavating machine and more particularly to that type of machine which is commonly known as a stripping shovel and which is used for removing the over- 5 burden from deposits of coal, ore or the like. In operation such a machine usually stands on the bottom of the cut and the spoil, or that portion of the overburden which is removed at each operation, is elevated, swung laterally beyond the in side of the cut and there deposited on the spoil bank. This operation requires the use of a relatively long boom and economy of operation requires the use of an excavating dipper of large capacity. The operations of filling, elevating and swinging the heavily loaded dipper imposes severe strains on the boom, such as the flexing of the intermediate portion of the boom under the thrust of the dipper handle while the dipper is being crowded into the bank and the torsional strain due to the inertia of the loaded dipper during the swinging operation. As a result it has been found impractical to utilize a boom having a length greater than from ninety 25 to one hundred feet and with this length of boom the depth of overburden which can be removed is limited to approximately forty-five feet.

One object of the present invention is to provide a machine of this type with which over- 30 burden may be removed to a substantially increased depth, thereby rendering available deposits of coal and ore which it is not practical to uncover with the present machines.

A further object of the invention is to provide 35 such a machine with two separate excavating elements adapted to operate respectively upon lower and upper portions of the bank which is being excavated, thus rendering it possible to divide the load on the boom, and. to support the 40 heavier portion of the load on a relatively short radius and to impose only a relatively light load on the outer end of the boom.

A further object of the invention isto provide such a machine with a boom comprising two sections arranged end to end and connected one to the other, the excavating elements being mounted on the respective sections of the boom and being separately operated. 50 A further object'of the invention is to provide such a boom in which the two sections are pivotally connected one to the other and means are provided for restraining the relative movements of the two sections about their pivotal connection.

Other objects of the invention will appear as the mechanism is described in detail.

In the accompanying drawing Fig. 1 is a side elevation of a portion of an excavating machine embodying my invention; and Fig. 2 is a side ele- 5 vation of a portion of a slightly modified form of boom.

In this drawing I have illustrated one embodiment of the invention, together with a minor modification thereof, and the drawing is largely l diagrammatic as the various elements entering into the organization may take various forms. In this drawing I have shown the invention as applied to a stripping shovel of a known type ;1:: which comprises a base mounted on traction lo devices 6 and having rotatably mounted thereon a platform I which carries the usual boom supporting frame or gantry 8 and cab 9. Mounted on the revolving platform 1 is a boom of relatively great length on which two excavating elements are mounted and are spaced different distances from the point of the boom. The boom itself and the excavating elements may take various forms and, as here shown, the boom comprises an inner section It! which is mounted at its lower end or foot on the revolving platform, as shown at H. One excavating element is carried by this boom section and comprises a dipper handle l2 mounted on the boom section between the ends thereof for longitudinal movement transversely to the boom section and for pivotal movement with relation thereto. The dipper handle is provided with a toothed rack l3 which meshes with a pinion I4 carried by the boom section and driven by the usual crowding mechanism, which is shown at I5 as mounted on the boom section. The dipper handle carries at its outer end the usual excavating dipper I6 which is connected by a cable H with a sheave H3 at the outer end of the boom section It! and this cable I! extends inwardly to the usual hoisting mechanism on the revolving platform. The boom also comprises an outer section l9 arranged substantially in line with the inner boom section I and connected thereto. This outer boom section is also provided with an excavating element comprising a dipper handle 20 which is operated by crowding mechanism 2| carried by the outer boom section, and it has at its outer end a dipper 22 connected by a cable 23 with a sheave 24 at the outer end or .point of the outer boom section, this cable also extending inwardly to hoisting mechanism on the revolving platform. The hoisting cables I! and 23, which operate the respective excavating elements or dippers, are pref 5 erably extended to and controlled by separate hoisting mechanisms which may conveniently be under the control of separate operators and which are not here shown as they may be of ordinary construction. In the form shown in Fig. 1 the two boom sections are separately supported in their properly inclined positions, the inner boom section EB having its outer end connected by a suitable cable support 25 with the gantry 8 and the outer boom section having its outer end similarly connected by a cable support 26 with the gantry 8. The two boom sections are thus supported normally in fixed relative positions but their angle of inclination may be changed or they may be adjusted with relation one to the other by a manipulation of the supporting cable 25 and 26 in a well known manner. In the operation of the machine the inner dipper I6, which is preferably of a capacity of approximately twice the capacity of the outer dipper 22, is caused to operate on the lower portion of the bank along the line 21, as shown in Fig. 1, while the outer dipper 22 is caused to operate on the upper portion of the bank, as along the line 28. In this manner the relatively large inner dipper makes a longer cut and carries the heavier load and as it is mounted on a relatively short radius the strains imposed thereby upon the boom are relatively small. The outer dipper takes a smaller cut and carries a lighter load which is imposed upon the boom on a longer radius but due to its relatively light weight does not impose undue strains upon the boom. The inner boom and its dipper may be of a size and capacity similar to those now employed on large capacity machines and this dipper can remove overburden of a depth equal to the maximum which can be removed by the present machines, and the outer dipper removes an additional depth of overburden, of approximately half the depth of the overburden removed by the inner dipper, thus increasing the depth of overburden that can be removed by approximately fifty percent. When the cuts have been made and the two dippers have been elevated the boom is swung to the side of the cut and spoil is discharged from the inner dipper on the spoil bank 29 and the spoil from the outer dipper is discharged on a spoil bank 3!).

In the construction here shown the inner boom and its excavating element are complete in themselves, and may be used independently of the outer boom section. This outer boom section constitutes a supplemental boom which is connected with the outer end of the main or inner boom to form an extension thereof, thus permitting the shovel to be operated with either a single dipper or with two dippers.

The two boom sections are preferably pivotally connected one to the other so that transverse strains imposed thereon by the dipper thrust or otherwise will be compensated for by the yielding of the pivotal connection and the boom sections themselves thus protected against flexing. Inasmuch as the dipper handles are connected with the boom sections at substantial distances from the pivotal connection between the two sections there will ordinarily be little tendency for the connected ends of the two sections to move upwardly, as the boom is supported in the usual manner and the Weight of the sections will tend to hold the same against elevation. Should there in any case be a tendency for the boom sections to have relative movement about their pivotal connection this movement can be restrained by suitable mechanism, such as the structure shown in Fig. 2. As there shown, a strut 3| is connected with the boom adjacent to the pivotal connection between the two sections thereof and extends upwardly and rearwardly from the boom. The upper or outer end of the strut is connected by a strut 32 with the outer boom section l9 and by a strut 33 with the inner boom structure, thus providing a truss which will prevent any substantial relative movement of the boom sections but will permit the connected ends of the sections to yield sufficiently to take care of the strains imposed thereon. When this truss structure is used it is unnecessary to provide the cable support for the outer boom section but the boom as a whole may be supported by the cable support 25.

While I have shown and described one embodiment of my invention I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In an excavating machine, an inclined boom mounted for swinging movement about a vertical axis, a plurality of excavating elements mounted at fixed points on said boom and spaced different distances from the foot thereof, means for operating said excavating elements to cause them to operatively engage the bank which is to be excavated at difierent levels, and means for swinging said boom to simultaneously move said excavating elements to dumping positions at difierent levels.

2. In an excavating machine, an inclined boom mounted for swinging movement about a vertical axis, a plurality of excavating elements mounted at fixed points on said boom and spaced different distances from the foot thereof, separately operable means for causing said excavating elements excavated at different levels, and means for actuating said boom to simultaneously swing said excavating elements to dumping positions at difierent levels.

3. In an excavating machine, an inclined boom,

an excavating dipper of large capacity supported on said boom for operation at one level, an excavating dipper of relatively small capacity supported on said boom for operation at a higher level, and means for operating said dippers to cause the same to engage different parts of the bank which is to be excavated.

4. In an excavating dipper, a boom, a plurality of dipper handles mounted on said boom and spaced different distances from the point thereof, dippers carried by. said dipper handles, means for operating said dippers to cause the same to engage different parts of the bank which is to be excavated, and means for swinging said boom to move said dippers simultaneously to dumping positions, said dippers and their supporting handles being so arranged that said dippers will engage said bank at different levels and will be supported in dumping positions at different levels.

5. In an excavating machine, a boom, a plurality of dipper handles mounted on said boom and spaced different distances from the point thereof, dippers carried by said dipper handles, separate crowding mechanism for each dipper handle, a seperate hoisting line for each dipper, and means for swinging said boom to move said dippers simultaneously to dumping positions, said dippers and said handles being arranged to cause said dippers to engage said bank at different 40 to operatively engage the bank which is to be levels and to be supported at different levels when in dumping positions.

6. In an excavating machine, a boom comprising two sections arranged end to end and connected one to the other, supporting means for said boom sections, excavating dippers carried by the respective boom sections and supported thereby at different levels in both their excavating positions and their dumping positions, and separate means for operating said dippers.

7. In an excavating machine, a boom comprising two sections arranged end to end and pivotally connected one to the other, supporting means connected with each boom near the outer end thereof, excavating dippers carried by the respective boom sections and supported thereby at different levels, and separate means for operating said dippers to cause the same to engage difierent parts of the bank while said boom is in a given position.

8. In an excavating machine, a boom comprising two sections arranged end to end and pivotally connected one to the other, supporting means for said boom, excavating dippers supported at different levels by the respective boom sections,

separate means for operating said dippers, and means for restraining the relative movement of said boom sections about said pivotal connection.

9. In an excavating machine, a main boom, means for supporting the same, an excavating dipper carried by said boom and arranged to operate on a lower portion of the bank which is to be excavated, means for operating said dipper, a supplemental boom mounted on the outer end of said main boom, an excavating dipper carried by said supplemental boom and arranged to operate on a higher portion of said bank and means for operating the last mentioned dipper.

10. In an excavating machine, a boom comprising two sections arranged end to end and pivotally connected one to the other, supporting means for said boom, a dipper handle mounted on each boom section, a dipper carried by each handle, separate means for operating each dipper and its handle, a strut connected at one end with said boom adjacent to said pivotal connection and extending transversely thereto, and other struts connecting the other end of the first mentioned strut with the respective boom sections.

DWIGHT J. SHELTON. 

